This invention relates to filter devices for use in fish aquariums, and more particularly, to a compact aquarium filter device of the type having a combination of differing filter elements and a concentric tube arrangement which permits drawing water through parallel filters with a single pump.
In the field of aquarium maintenance, the use of filter devices has long been recognized as an effective method of removing debris, biological waste and undesirable chemicals from an aquarium tank. Many of the filter systems were comprised of a plurality of different filter elements connected in a tandem or series arrangement. Such a series arrangement tended to dramatically slow down the filtering process since the entire process was limited by the slowest filter element. The slowest filter element tended to be the "dry" biological filter element. Substantial time was required for the tank water to cascade across the biological element to aerate the bacteria residing in the filter.
In the past, efforts were made to reduce the filtering cycle time across the biological filter by increasing the surface area thereof. Although the cycling time may have been reduced, the size of the "dry" biological filter was substantially larger and thus incompatible for use in a compact filter device designed for being mechanically attached to a side of the aquarium.
Other efforts in the past have been directed to problems associated with aquarium filters. In particular, there is known a recirculation water filtration and aeration system designed specifically for aquariums. Water drawn from the aquarium tank was prefiltered in a water level control device before being conveyed to an external filter means. The filtered water or filtrate was dispensed from a spray bar having a plurality of horizontally spaced small openings for discharging the filtered water to a pair of filter media trays which contained filter media and aerobic bacteria. The function of the filter media and aerobic bacteria was to clean the aquarium water as it was percolated downward across the filter media and into a reservoir. The filtered water was drawn from the reservoir by a pump which discharged the filtered water through a tube to the top of the aquarium tank.
Another attempt to solve the problems associated with aquarium filters was directed to an aquarium filtration system which was comprised of an assembly of coaxial tubes. The aquarium filtration system was located beneath a surface level of gravel at the bottom of the aquarium tank. The under-gravel filtration system filtered the water from the upper tank by employing the existing aquarium gravel system in conjunction with the biological action of an additional fine sand filter supported on a screen mesh. The combination of the aquarium gravel system and the fine sand filter provided double filtration of the water whereby the clean filtered water was supplied through a supply tube but was not fed back to the biological fine sand filter thereafter.
Another water filter was directed to the use with aquariums wherein the water filter included a filter cartridge. The filter cartridge was comprised of an outer tube and a coaxial inner tube, both inner and outer tubes having perforations formed therein. However, the flow of fluid through the perforations formed into the inner tube also passed through the perforations formed in the outer tube. Since the two tubes drew fluid from the same chamber, distinctly different water levels for different filter elements within the water filter were not maintained.
Still another aquarium filtration system included a filter housing comprised of a first chamber, a second chamber and a third chamber. Each of the chambers could operate at a water level independent of the other two chambers. The variation in water level in the different chambers was responsive to the hydrostatic pressure and porosity of the filtering medium. Thus, the fluid level in any of the three chambers tended to rise when the filter media became plugged with impurities.
Finally, a self-cleaning aquarium system is known in the past and included a concentric tube arrangement whereby water was withdrawn from the aquarium tank through an outermost tube of the concentric tube arrangement. The aquarium water drawn from the tank through the outermost tube was directed to a plurality of openings where the water was then directed into a plurality of filters. After the filtration cycle, the filtered water was pumped back to the aquarium tank through an innermost tube of the concentric tube arrangement, the innermost tube being coupled to a pump mounted therein.
Hence, those concerned with the development and use of filtering systems in the aquarium maintenance field have long recognized the need for an aquarium filter comprised of a plurality of filtering elements packaged in a single compact unit wherein the filtering elements are connected in a parallel arrangement and the aquarium filter includes a concentric tube arrangement for directing aquarium water to and from distinct filtering elements, wherein only a single submersible pump is required for driving the aquarium water through the plurality of parallel connected filtering elements and the single pump is capable of maintaining multiple water levels for providing maximum operating efficiency of the aquarium filter.
Further, there is a recognized need for an improved aquarium filter which provides a more stable, stress-free environment for providing a better gas exchange, a more consistent pH level, a dissolved oxygen level content at or near saturation, advanced prefiltration with long periods between service intervals, a biological filter capable of filtering a higher aquarium population and having a faster response to changes in the biological load. The present invention fulfills all of these needs.